Method for forming tubular pipe coupling



July 19, 1966 D. D. BROWN METHOD FOR FORMING TUBULAR PIPE COUPLING Original Filed Jan. 24. 1962 INVENTOR. DELMO/V 7' D. BRO W/V BY WJW E KW United States Patent 3,261,735 METHOD FOR FORMlNG TUBULAR PIPE COUPLING Deimont I). Brown, North Baltimore, Ohio, assignor to The D. S. Brown Company, North Baltimore, Ohio, a corporation of Ohio Original application Jan. 24, 1962, Ser. No. 168,453, now Patent No. 3,177,015, dated Apr. 6, 1965. Divided and this application Mar. 12, 1965, Ser. No. 439,144 2 Claims. (Cl. 156-458) This application is a division of my copending application Serial No. 168,453, filed January 2 4, 1962, now US. Patent No. 3,177,015.

This invention relates to methods for the manufacture of pipe couplings.

One of the objects of the invention is to provide new and improved methods for forming pipe couplings, which methods form inexpensive and long lasting pipe couplings.

Another object of the invention is to provide new and improved methods for forming pipe couplings, which methods are characterized by uncomplicated installation techniques.

Other objects and advantages of the invention will be apparent by reference to the following description in conjunction with the accompanying drawings in which FIGURE 1 is an elevational view of a pipe coupling embodying the invention;

FIGURE 2 is a cross sectional view on an enlarged scale of the pipe coupling shown in FIGURE 1;

FIGURE 3 is a cross sectional view showing the pipe coupling of FIGURE 1 in assembled relationship with a pair of pipes or conduits; and

FIGURE 4 is an end view of the assembly taken along the line 44 of FIGURE 3.

In accordance with the invention, a pipe coupling is provided which comprises an annular piece of resilient sponge elastomer shaped to form opposed openings into which opposing pipe ends are adapted to fit and engage the interior sides of said openings, and an annular rib integrally tormed at an intermediate position between said openings and extending radially inwardly a distance not substantially greater than the Wall thickness of said pipe ends. A further feature of the invention is the pro vision of a structure in which the interior walls of said coupling has two, aligned frusto-conical segments tapering from the base of said annular rib toward opposite entrants of the opening. Another feature of the invention is the provision of an annular internal cavity within said annular piece and at least partially within said rib to permit lateral compression by said pipe ends. A further feature of the invention is the provision of an annular recess in the exterior of said annular piece adapted to receive a locking band or clamp.

In the drawings the pipe coupling shown consists of an annular piece of resilient sponge elastomer 1 which is shaped to form opposing openings 2 and 3 having interior surfaces 4 and 5 'which are frusto-conical and taper outwardly from the base of an annular rib 6. An annular internal cavity 7 is formed within the pipe coupling so that at least a part of the cavity extend-s with-in the annular rib 6. A recessed portion 8 is also formed on the exterior surface of the coupling to receive a clamping band 9 which is 'held in place in any suitable manner, for example, by means of a bolt 10 and a nut 11, as shown in FIGURES 3 and 4. The bolt 10 is inserted through opposing upwardly extending flanges 12 and 13 formed on opposite ends of the clamping band 9.

As shown in FIGURE 3, when opposing pipe ends 14 and 15 are inserted into the pipe coupling 1, the frustoconical surfaces 4 and 5 are pushed outwardly to a substantially cylindrical shape and exert gripping pressure on 3,261,735 Patented July 19, 1966 the exterior surfaces of the pipe due to their inherent resilience and the fact that they are displaced from their normal positions. The internal cavity 7 provides compensation for the stresses placed on the pipe coup-ling when the pipe ends are inserted.

In clamping the pipe coupling, it is sometimes desirable to insert a washer or other suitable stop, not shown, in the space between the flanges =12 and 13 to prevent overcompression of the sponge when the clamp is tightened.

It is important for the purpose of the invention that the pipe coupling be made irom a resilient sponge elastomer. Sponge elastomers are well known but are not ordinarily employed in pipe couplings. By the term sponge elastomer is meant an elastomer in which cells or internal cavities have been formed throughout the elastomer by homogeneously incorporating with the elastomer a blowing agent which evolves a gas or vapor. Open cell sponge elastomers can be used but closed cell sponge elastomers are preferred. Examples of suitable elastome-rs are rubber, synthetic rubber, neoprene, polyurethane, and other polymerization products as defined in Hackhs Chemical Dictionary, Third Edition, page 295. The use of neoprene is preferred for the practice of this invention because of its physical properties and especially because of ageing and weathering properties, its resistance to deterioration by oils, and its resistance to deterioration by substances normally carried in pipe lines. Exam-pies of suitable blowing agents are diazoarninobenzene, urea, biuret, vmixtures of urea and bi-uret and dinitrosopentamethylenetetramine.

The preparation of the sponge elastomeric material is carried out in a conventional manner by mixing the elastomer with the bloWing agent and other conventional ingredients, such as waxes, carbon black, process oils, activators for the blowing agent, if required, and antioxidants, at temperature below the temperature at which the blowing agent evolves the desired gases and/or vapors, then extruding the mixture to shape and applying heat to produce a sponge elastomer. In carrying out the invention it is preferable to extrude the mixture in a continuous piece or strip, cut the strip into smaller pieces and then cement the ends of the out pieces together to form an annular pipe coupling as shown in FIGURES 1 and 2. It is also possible to mold the pipe coupling in dies in its final form thereby avoiding the cementing operation but the molding process is more expensive due to the cost of the molds, the labor involved and the slower rate of production.

When it is desired to make the pipe coupling with an open cell structure, one procedure is to extrude an open cell sponge and dip the extruded piece into a solution of a sealing composition such as solvent dispersed rubber or neoprene or polyurethane. Instead of dipping, the piece can be sprayed with a polyurethane solution containing a catalyst to form a skin over the cell structure.

The invention makes it possible to provide a new and improved pipe coupling made from a material of the same type which has heretofore been used in many other applications, such as, sealing the doors and trunks of automobiles, but has not heretofore been employed in pipe couplings. The invention also provides a new and improved method for making such pipe couplings.

Thus, my process comprises extruding a cellular-elastomer in the form of a strip having a bottom wall and an upper wall with an upwardly-projecting, longitudinal rib extending along the mid-portion of said strip and wall portions on opposite sides of said rib each sloping upwardly and outwardly from the base of said ri b to the respective longitudinal edges of said strip, forming in said rib and a portion of said strip below said base of said rib a longitudinal, narrow cavity, transversely cutting said extruded strip into pieces with lengths corresponding to the desired circumference of the pipe coupling, forming the respective pieces into rings with said bottom wall as the outer, annular wall and said upper wall as the inner, annular wall with the opposite ends of the respective pieces in abutment, and cementing the respective opposite ends of each strip together to form a hollow, cellular-elastomer coupling ring having normally frusto-conical, inner walls tapering from an axially central portion of said coupling ring to opposite ends thereof, said central portion including a cellular, elastomer, annular rib projecting into the central portion of said coupling ring, and said central portion having an enclosed, annular cavity with the outer, radial wall of said cavity located radially outwardly of the inner wall of said central portion and the inner, radial wall located in said rih for compensating stresses in said coupling ring when pipe ends are inserted in said coupling ring.

The invention is hereby claimed as follows:

1. A process for making a pipe coupling which comprises extru-ding a cellular-elastorner in the form of a strip having a bottom wall and an upper Wall with an upwardly-projecting, longitudinal rib extending along the mid-portion or" said strip and wall portions on opposite sides of said rib each sloping upwardly and outwardly from the base of said rib to the respective longitudinal edges of said strip, forming in said rib and a portion of said strip below said base of said rib a longitudinal, narrow cavity, transversely cutting said extruded strip into pieces with lengths corresponding to the desired circumference of the pipe coupling, forming the respective pieces into rings with said bottom wall as the outer, annular wall and said upper wall as the inner, annular wall with the opposite ends of the respective pieces in abutment, and cementing the respective opposite ends of each strip together to form a hollow, cell-ular-el astomer coupling ring having normally frusto-conical, inner walls tapering from an axially central portion of said coupling ring to opposite ends thereof, said central portion including a cellular-elastomer, annular rib projecting into the central portion of said coupling ring, and said central portion having an enclosed, annular cavity with the outer, radial wall of said cavity located radially outwardly of the inner wall of said central portion and the inner, radial lWHll located in said rib for compensating stresses in said coupling ring when pipe ends are inserted in said coupling ring.

2. A process as claimed in claim 1 wherein said cellular elastome-r is -a closed Cfilil, cellularelastomer.

References Cited by the Examiner UNITED STATES PATENTS 2,388,297 11/1945 Slaughter 156-304 3,027,286 3/1962 Kurhan l56264 3,068,136 11/l96'2 Reid l56-244 X EARL M. BERGERT, Primary Examiner.

HAROLD ANSHER, Examiner. 

1. A PROCESS FOR MAKING A PIPE COUPLING WHICH COMPRISES EXTRUDING A CELLULAR-ELASTOMER IN THE FORM OF A STRIP HAVING A BOTTOM WALL AND AN UPPER WALL WITH AN UPWARDLY-PROJECTING, LONGITUDINAL RIB EXTENDING ALONG THE MID-PORTION OF SAID STRIP AND WALL PORTIONS ON OPPOSITE SIDES OF SAID RIB EACH SLOPING UPWARDLY AND OUTWARDLY FROM THE BASE OF SAID RIB TO THE RESPECTIVE LONGITUDINAL EDGES OF SAID STRIP, FORMING IN SAID RIB AND A PORTION OF SAID STRIP BELOW SAID BASE OF SAID RIB A LONGITUDINAL, NARROW CAVITY, TRANSVERSELY CUTTING SAID EXTRUDED STRIP INTO PIECES WITH LENGTHS CORRESPONDING TO THE DESIRED CIRCUMFERENCE OF THE PIPE COUPLING, FORMING THE RESPECTIVE PIECES INTO RINGS WITH SAID BOTTOM WALL AS THE OUTER, ANNULAR WALL AND SAID UPPER WALL AS THE INNER, ANNULAR WALL WITH THE OPPOSITE ENDS OF THE RESPECTIVE PIECES IN ABUTMENT, AND CEMENTING THE RESPECTIVE OPPOSITE ENDS OF EACH STRIP TOGETHER TO FORM A HOLLOW, CELLULAR-ELASTOMER COUPLING RING HAVING NORMALLY FRUSTO-CONICAL, INNER WALLS TAPERING FROM AN AXIALLY CENTRAL PORTION OF SAID COUPLING RING TO OPPOSITE ENDS THEREOF, SAID CENTRAL PORTION INCLUDING A CELLULAR-ELASTOMER, ANNULAR RIB PROJECTING INTO THE CENTRAL PORTION OF SAID COUPLING RING, AND SAID CENTRAL PORTION HAVING AN ENCLOSED, ANNULAR CAVITY WITH THE OUTER, RADIAL WALL OF SAID CAVITY LOCATED RADIALLY OUTWARDLY OF 